Previously, inadvertent multiple picks of the top few sheets of paper in an infeed mechanism have been reduced to some extent by, for example, supplying a frictional force against those sheets beneath the top sheet in the infeed stack. One such mechanism is described in co-pending U.S. patent application Ser. No. 07/954,541 entitled "Paper Pick-up System for Printers", which was filed Oct. 29, 1992, and which is subject to common ownership herewith. Described therein is a pivotally-operable, spring-returnable separator located adjacent and beneath the infeed rollers of a sheet pick mechanism of an ink-jet printer, the separator having a wear-resistant, upstanding portion rearwardly adjacent a frictionally adherent pad. The separator's pad opposes advancement of a next-to-top sheet in the infeed paper stack while the top sheet of the stack is pulled thereacross by one or more rollers. While such a separator pad is effective in opposing advancement of a next-to-top sheet, there typically remains undesirable advancement, of the media sheets below the top sheet that has just been advanced for printing, toward the feed zone, resulting in an uneven leading, or `downstream`, or `forward`, top edge of the paper sheet stack.
Co-pending U.S. patent application Ser. No. 08/055,627 entitled "Sheet Media Feed System", filed Apr. 30, 1993 by co-inventors Allan G. Olson, Robert K. Beretta, Michael K. Bowen and James O. Beehler, and subject to common ownership herewith, describes an improved paper sheet infeed mechanism that selectively brings a separator from an at-rest position into engagement with the sheet media so as to effect pick-up of a single sheet. Once the sheet is picked, and before further downstream processing (e.g. printing) begins, the separator is returned to its at-rest position until the next sheet is to be picked. Reliable delivery of sheet media to the input port, e.g. of a printer, is thus effected by moving the separator away from the sheet media to enable the invented realignment mechanism described herein to operate. The disclosure of that application is incorporated herein by this reference.
Slidable stacked-paper input trays for printers have been proposed, wherein the trays have manual means for grippingly capturing the entire paper stack when the tray is pulled away from the printer's feed zone. Such an improved tray is described in co-pending U.S. patent application Ser. No. 07/954,766 entitled "Printer Paper Pullout Apparatus", filed Sep. 30, 1992 and subject to common ownership herewith. The paper capture means described and illustrated therein is marginally effective in preventing multiple picks, since the top few unevenly advanced sheets also are captured and removed from the feed zone. Unfortunately, it requires that the tray be fully extended any time it is desired to add paper to the tray.